Objective: To develop a method by ion chromatography with suppressed conductivity detection for the determination of EDTA and nitrate ion in vitamin B1 injection. Method: Chromatographic separation was achieved on an IonPac AS 11-HC column (4.0 mm×250 mm) with an IonPac AS 11-HC guard column (4.0 mm×50 mm) and an ASRS 300 suppressor (4 mm). The eluent was 12 mmol·L-1 NaOH with flow rate 1.0 mL·min-1. The suppressor current was 60 mA

and the conductivity detector temperature was set at 35℃ while the column temperature was maintained at 30℃. The injection volume was 25 μL. Result: The limit of determination of EDTA and nitrate ion were 0.29 mg·L-1 and 0.01 mg·L-1 respectively. The standard curve of EDTA was linear in the concentration range of 1.19-23.8 mg·L-1 and the correlation coefficient was 0.999 7.The recoveries of the EDTA were between 98.2%-100.6%. The standard curve of nitrate ion was linear in the concentration range of 1.0-10.0 mg·L-1 and the correlation coefficient was 0.999 6.The recoveries of the nitrate ion were between 97.9%-99.5%. Conclusion: The proposed method shows high selectivity

sensitivity and good results. It is proved to be rapid and convenient. It can be employed for the quality control and research of EDTA and nitrate ion in injection products.